The process of metastasis causes 90% of solid tumor cancer deaths, yet there is little known about the contributing factors to this deadly stage of disease. There are few treatment options available for patients who harbor metastases, especially in those patients whose metastatic disease is more advanced. More direct studies of metastasis are necessary to elucidate biological driving mechanisms, identify effective therapeutic targets and improve overall survival. Pancreatic ductal adenocarcinoma (PDAC) has an extremely low survival rate and many patients are diagnosed in the metastatic stage. The hypothesis of this proposal is that the development of lethal pancreatic cancer metastasis depends on subclonal evolution occurring within the primary tumor. This proposal has two Aims to address this hypothesis. For the first aim, the phylogenetic relationships between organ-specific metastases will be determined. Deep sequencing of all gross metastases present in four rapid autopsy patients will reveal the phylogenetic relationships of each metastasis to each other. The second aim will determine if metastases in different target organs within the same patient originate from a single or multiple metastatic subclones from the matching primary tumor. For this aim, the deep sequencing of multiple physically distinct sections of the primary tumors of the same patients in Aim 1 will elucidate the genetic life history of each carcinoma and allow for the geographical mapping of the number and location of metastatic subclones. Thus, this study will reveal the phylogenetics and evolutionary history of metastasis in PDAC, improving the overall knowledge and therapeutic targeting of this lethal stage.